C = 38+0.7*(Y - 10 - 0.1 * Y) Doesn't know Y, and we don't need to know Y!
C will be egal with 31 + 0.63 * Y, but I don't know that how does it became to "C = 31+0.63*Y"
Please show me the step by step solving this

Step-by-step explanation:i

step-by-step explanation:

y = | -2(-2) |     →     y = | 4 |     →     y = 4       ⇒   (-2, 4)

y = | -2(-1) |     →     y = | 2 |     →       y =   2       ⇒   (-1, 2)    

y = | -2(0) |     →     y = | 0 |     →       y = 0         ⇒   (0, 0)

y = | -2(1) |   c →     y = | -2 |     →     y =   2         ⇒   (1, 2)    

y = | -2(2) |     →     y = | - 4 |     →     y =   4         ⇒   (2, 4)